Battery cross-over wiring

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littlebookworm

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The previous owner of our Cruisers had a battery cross-over set of switches installed, which was a great help when one of the starting batteries died. However, it is down in the engine bay, requiring removing the cockpit table, unsnapping the carpet, lifting the hatch, and crawling down into the engine bay to work the switches. I know some newer boats come with a cross-over, relay controlled, to switch batteries. I'd like to redo the system on our boat. Does anyone have a wiring diagram for a cross-over system? I can read and follow schematics with no problem. Thanks. Hy
 
Blue Seas has diagrams but the relays in them are for automatic battery charging rather than remote electronic switching:

https://www.bluesea.com/resources/170/Battery_Management_Wiring_Schematics_for_Typical_Applications (Select your system)

You can just eliminate the ACRs from the circuits if not desired. Why not just add min.cable length needed and mount the switches up above where they are readily accessible? ( You could include main On/Off switches right next to the batteries too but that starts to get cumbersome.)
 
It's basically just a big relay / solenoid. You have two large terminals where the battery cables connect (just like the manual switch you have) and two smaller terminal which receive power from a helm switch when you need to parallel. Pretty basic.
That said, you need to figure out why you run down one battery as everytime you do, the battery takes a hit
 
Thanks for the info. The battery died from old age. The other starting battery had to be replaced a few weeks latet. Both were over four years old.
 
Not exactly sure what you're talking about...but a battery switch would do the same thing.

Oh I see. Doing a remote switch. Like jumping a car without the charging system of the second car to back up the battery. The charging system taking place of the 'Make before Break' of a battery switch.

You would need two remote switches with 3 constant on solenoids using a criss-cross pattern. Been a while since I had to make one up.

My brain just doesn't work with involved thinking...come to think of it, my brain has trouble thinking...
 
Two remote switches and 3 constant on solenoids?.

No, all she needs is a basic battery parallel system where the positives of both banks are linked together by a solenoid instead of battery switch.
 
That is for paralleling the banks , which for most of us is only done in special circumstances.... and can be detrimental if there is a bad battery involved. But I may be hung up on semantics.

My read on littlebookworm's request was he is looking for a way to more conveniently (remotely) control normal independent, or crossover hookups with or w/o paralleling, including leaving a bad bank out .
I expect that could still be done with the solenoids(more) , or just moving existing 4-way switches up for same operation but readily accessible at the shortest-cable position.
 
Thanks for all the possibilities. Right now there are three two-way switches located in the forward part of the engine bay. I was hoping there was an(relatively, after all, this is a boat) inexpensive way of setting up relays and a master switch at the helm which would be operating slave switches in the engine bay to switch between batteries if ever needed. Right now the outer switches are 'on' and the center switch is 'off.' Moving the center switch to 'on' enables me to have a second battery available for starting either engine. The house n=battery is not involved. I think the easiest way would be to move the entire panel of switches and their mounting board to the inside of the transom shore-power cable locker and to run new cables from the switches to the batteries. That way the cross-over is relatively accessible without any table or deck disassembly and is still out of the way. Another winter project! Hy
 
Yeah, the idea is to swap a house batt into the starting circuit while taking the starting battery out of the circuit. You don't want the house batt trying to charge the bad starting batt which it will do if just hooked up in parallel. I still think you can do it with two batt switches...3 if two engines.
 
You could run cables from your outer # 1 and #2 battery 2-way On/Off switches up to two 4-way OfF/1/Both/2 switches at the cable locker where you can access them .
Run #1 cable from below to #1post on the 1st 4-way SW,... and from there over to #1 on the 2nd 4-way.
Run #2 cable to #2 on the 2nd 4-way,... and from there over to #2 post on the 1st 4 way.

That way you can start either engine on #1,#2 or Both batteries as desired . That would also retain possible switching ability down below when working down there if that is desireable (depending on upper switch positions.) But with that many connections it would behoove you to 1st clean well all original ring terminals and posts and apply a little protectant after installing the new cables to maintain low resistance going forward.
And keep in mind the extra run length when calculating gauge size.
 
Sandy and Charlie: Thanks, I've printed out your suggestions and will use them off-season to redo the cross-over switches. The way it's wired right now, I can isolate either starting battery while connecting the alternate starting battery, leaving out the house battery all-together. One of the changes I also want to make is to change the tray for the house battery so I can put in a larger one, another winter project! Hy
 
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